Real-time detection of asymmetric surface deformation and field stress in concrete-filled circular steel tubes via multi-vision method

Aiming at the characteristics of full-field asymmetric surface deformation on the surface of concrete-filled steel tubular columns, a mark-free multi-vision measurement method is proposed, and the vision system structure, curved surface measurement principle, image acquisition, preprocessing algorithm and 3D point cloud reconstruction algorithm are illustrated. An image stitching algorithm is proposed to calculate the deformation radius of the asymmetric surface and the radius of curvature and its height of the largest deformation section. In the seismic test, the stereo vision system developed by the authors is used to automatically collect and process the three-dimensional deformation and field strain of the specimens. Besides, the three-dimensional point cloud reconstruction algorithm is proposed to realize the full-field three-dimensional deformation image reconstruction. The comparison results indicate that the multi-ocular vision measurement method can measure the deformation process of the asymmetric surface and the exact value of the full field strain, its accuracy meets the engineering requirement. The proposed method can evaluate the asymmetric deformation of the structure subjected to impact loads or vibration and provide real-time decision data for structural health monitoring.